Abstract:On the basis of the borehole strain observations at Guza and Xiaomiao stations in the National Digital Seismological Observational Networks, the coupling coefficients and phase lag of tidal response are fitted by using solid tidal strain model. With comprehensive observation model which contains tidal response rate and phase lag and effects of air pressure disturbance, the changes within the tidal band are analyzed. The spatial and temporal changes are discussed from characteristics of geological structure and medium. The results show that anomalies of tidal response parameters and high frequency disturbance had been observed from several months to a year before Wenchuan Ms8.0, Huili Ms6.1 and Yaoan Ms6.0 earthquakes. The strain rosette at Guza station is stable relatively, the deformation is mostly dominated by geological structure.